For example, there is a multi-air-conditioning apparatus for a building that performs air conditioning by exchanging heat between a refrigerant, which circulates between an outdoor unit and a relay unit, and a heat medium such as water, which circulates between the relay unit and indoor units. During the heat exchange, power for conveying the heat medium is reduced so as to save energy (see Patent Literature 1, for example).
Furthermore, there is an air-conditioning apparatus devised with a countermeasure for refrigerant leakage in a case in which hydrocarbon is employed as a refrigerant. In this air-conditioning apparatus, a refrigerant passage is shut-off with a solenoid valve when there is refrigerant leakage (see Patent Literature 2, for example).
Moreover, there is an air-conditioning apparatus that averts explosion in a case of refrigerant leakage when a combustible refrigerant is employed. In this air-conditioning apparatus, a damper for discharging the refrigerant is activated when leakage of the refrigerant is detected by a refrigerant leak sensor disposed inside a housing of an outdoor unit. Further, the air-conditioning apparatus is configured to operate an air-sending device such that air is sent into the housing (see Patent Literature 3, for example).